The explorer thought to himself: It's always a ticklish matter to intervene decisively in other people's affairs. He was neither a member of the penal colony nor a citizen of the state to which it belonged. Were he to denounce this execution or actually try to stop it, they could say to him: You are a foreigner, mind your own business. He could make no answer to that, unless he were to add that he was amazed at himself in this connection, for he traveled only as an observer, with no intention at all of altering other people's methods of administering justice. (19)
The explorer is quite aware of his status as a foreigner, and feels it commits him to not interfering in other people's affairs. He's just there to watch. He would say he has no "right" to intervene, since he's not a member of the community he's watching (that's in fact exactly what he'll say when the officer decides to put himself into the machine). This makes him sound very much like an anthropologist.
Yet here he found himself strongly tempted. The injustice of the procedure and the inhumanity of the execution of the procedure were undeniable. No one could suppose that he had any selfish interest in the matter, for the condemned man was a complete stranger, not a fellow countryman or even at all sympathetic to him. (19)
This particular situation challenges the explorer's willingness to show "tolerance." One wonders if this is the first time. Notice that he justifies his temptation to intervene as a matter of principle, not because he feels any sympathy for the condemned man. He says he does not. Rather, the colony's judicial procedure disagrees with his own understanding of what is right.
[The officer:] "Although he is powerful enough to take measures against me, he doesn't dare to do it yet, but he certainly means to use your verdict against me, the verdict of an illustrious foreigner." (25)
Even without the explorer himself taking any action, his mere presence in the colony puts him in the middle of a struggle between the new Commandant and the officer. Both assign him a special prestige as a foreigner, and want to use it to justify their own positions in the colony.
[The officer:] "I can see him, our good Commandant, pushing his chair away immediately and rushing onto the balcony, I can see his ladies streaming out after him, I can hear his voice – the ladies call it a voice of thunder – well, and this is what he says: 'A famous Western investigator, sent out to study criminal procedure in all the countries of the world, has just said that our old tradition of administering justice is inhumane. Such a verdict from such a personality makes it impossible for me to countenance these methods any longer.'" (25)
This is where we learn that the explorer is actually engaged in a far-reaching effort to observe other justice systems. It also makes clear that his prestige stems from the fact that he's from "the West," which has more enlightened, more modern, standards of justice and humaneness. The new Commandant hopes to use that to attack the old traditions of the colony.
If the judicial procedure which the officer cherished were really so near its end – possibly as a result of his own intervention, as to which he felt himself pledged – then the officer was doing the right thing; in his place the explorer would not have acted otherwise. (42)
The explorer admires the depth of the officer's dedication to his tradition, even if he finds the tradition barbaric. Does that mean he's started to become convinced by it, or does the explorer just admire any person who clings strongly to their beliefs? This passage leaves open the question of whether the explorer feels himself guilty in some way for destroying the officer's tradition, or whether he does not.
"It's a foreigner," ran the whisper around him, "he wants to see the grave." (43)
The explorer is identified by the other people of the colony as a foreigner when he goes to see the commandant's grave. It seems as if they want to show him that they themselves find their own former tradition and past ridiculous, and want him to support them in that.
They could have jumped into the boat, but the explorer lifted a heavy knotted rope from the floor boards, threatened them with it, and so kept them from attempting the leap. (44)
Although we don't get any description of what he's feeling internally, it seems clear from the explorer's actions that he wants to leave the colony and everything he saw there behind. He's quick to escape, and he doesn't want to take any part of it with him. Something has deeply disturbed him.